Many different types of traffic channeling devices have been utilized previously. One type that has been widely used comprises a hollow drum made of a relatively lightweight plastic material which will not cause damage to a vehicle if the vehicle should accidentally strike the drum.
Because such hollow plastic drums are relatively light in weight, some type of ballast is needed to prevent the drums from being inadvertently blown over or moved about by the wind and/or air blasts produced by passing vehicles. One common form of ballast consists of sandbags which may be placed against the base of the drums.
The problem with using sandbags as ballast is that many applications require at least two sandbags, each weighing between 35 and 50 pounds, to hold each drum in place. Not only is it necessary to fill the sandbags, the sandbags must be transported and positioned in place on the drums at the job site, which is backbreaking work because they are so heavy and significantly adds to the time and labor of setting up the drums. Also, sandbags are susceptible to breakage and the potential danger of spreading loose sand on the roadway.
Sand-filled plastic bases as well as sandbags placed on top of plastic bases have also been used as ballast for breakaway drums that fit over the bases. The problem with these is that the bases must either be filled with as much as 60 pounds of sand or sandbags must be placed against the bases to hold the drums in place, which makes them difficult to set up and install. Moreover, plastic bases have a tendency to walk or creep on the ground due to wind or vacuum caused by passing vehicles and the like. Also, an inspector cannot make a drive-by inspection to determine whether the drums that use sand-filled bases as ballast are properly ballasted. In addition, it is costly to produce breakaway drums that are not susceptible to being blown or dislodged from the bases by wind or vacuum of passing vehicles and yet will readily allow the drums to break away from the bases under impact by a vehicle. Even if the drums do properly break away only on impact, some damage may still result to the vehicle if the vehicle should drive over the sand-filled bases.
The use of heavy metal rings as ballast to hold traffic markers down and prevent them from being blown over is also generally known. However, metal rings must be quite heavy in order to give the markers the desired stability, which makes them difficult to handle and install. Moreover, there is still the danger that if one of the vehicles should drive over the metal rings, some damage to the vehicle may result.